Nozzles having a variable cross-section

ABSTRACT

A variable-section nozzle comprising a fixed structure embodying a fixed nozzle casing, a plurality of controlled flaps distributed around and in extension of the downstream portion of said fixed nozzle casing, a plurality of levers disposed in alternation with said controlled flaps, a plurality of connecting links and a plurality of mobile control elements, wherein each intermediate lever extends up to the neighbourhood of the respective central planes of two successive controlled flaps; and for each controlled flap, two associated connecting links are disposed substantially in the central plane of said flap.

United States Patent Camboulives et al.

NOZZLES HAVING A VARIABLE CROSS-SECTION Inventors: Andre Alphonse Mederic Leon Camboulives, Savigny-sur-Orge; Theophile Francois Le Maout, Cesson; Bernard Arthur Zibette, Vitry-sur-Seine, all of France Assignee: Societe Nationale dEtude et de 7 Construction de Moteurs dAviation de France, France Filed: Sept. 17, 1974 Appl. No.: 506,869

[30] Foreign Application Priority Data Sept. 21, 1973 France 73/33962 [52] US. Cl. 239/265.39 [51] Int. Cl. B64C 15/06 [58] Field of Search 239/265.39, 265.41; 60/271, 230, 232

[56] References Cited UNITED STATES PATENTS 2,990,029 6/1961 Keen 239/265.39

3,004,385 10/1961 Spears et a]. 239/265.41 3,537,647 11/1970 Camboulives et a]. 239/265.39 3,612,106 10/1971 Camboulives et a1. 239/265.39 3,837,580 9/1974 Camboulives et a1. 239/265.39

Primary Examiner-Lloyd L. King [57] ABSTRACT A variable-section nozzle comprising a fixed structure embodying a fixed nozzle casing, a plurality of controlled flaps distributed around and in extension of the downstream portion of said fixed nozzle casing, a plurality of levers disposed in alternation with said controlled flaps, a plurality of connecting links and a plurality of mobile control elements, wherein each intermediate lever extends up to the neighbourhood of the respective central planes of two successive controlled flaps; and for each controlled flap, two associated connecting links are disposed substantially in the central plane of said flap.

5 Claims, 9 Drawing Figures W v Q a C25 I 1 2 R l 103 F 17" u 171 M a 107 V 3 h 173a 773 & 1 2 I7 m 172b 112 N 1, a I

SHEET PATENTED AUG 1 2 I975 PATENTEB Auci 21975 SHEET PATENTEB AUG 21975 HLLI 1 NOZZLES HAVING A VARIABLE CROSS-SECTION BACKGROUND OF THE INVENTION The present invention relates in a general way to variable cross-section nozzles designed for incorporation in particular into jet engines such as turbojet engines.

It relates more particularly to a nozzle of the kind already described in the U.S. Pat. No. 3 537 647, which comprises a fixed structure embodying a fixed nozzle casing, a plurality of controlled flaps distributed around and in extension of the downstream portion of said fixed nozzle casing, each of which flaps extends to either side of a central plane containing the longitudinal axis of the nozzle, and is articulated, about a first geometric axis disposed substantially tangential in relation to the nozzle, to said fixed structure, a plurality of intermediate levers disposed in alternation with said controlled flaps, each articulated, about a second geometric axis substantially tangential in relation to the nozzle, to said fixed structure, a plurality of connecting links each of which is articulated on the one hand, about a third geometric axis substantially tangential in relation to the nozzle, to a controlled flap, and, on the other hand, about a fourth geometric axis substantially tangential in relation to the nozzle, to an intermediate lever adjacent said flap in order that each controlled flap is associated with two connecting links by means of which said flap is respectively attached to successive succesive intermediate levers, the assembly formed by said controlled flaps, said intermediate levers and said connecting links, constituting a kinematic chain which is closed around the nozzle, and a plurality of mobile control elements each of which corresponds with a controlled flap and makes it possible to pivot said flap about said first geometric axis in order to vary the transverse cross-sectional area (section) of the nozzle.

The object of the present invention is to improve a nozzle of the kind described hereinbefore with a view to achieving an improvement in the operation of the aforesaid kinematic chain. More precisely, the aim of the invention is to get rid of (or at any rate very largely reduce) certain parasitic couples which develop in the known kinematic chain, and to improve the efficiency of the transmission of forces between each control jack and the corresponding controlled flap.

SUMMARY OF THE INVENTION To this end, in a nozzle equipped with a kinematic chain as disclosed in the preamble, the invention provides that each intermediate lever extends up to the neighbourhood of the respective central planes of two successive controlled flaps, and that for each controlled flap, the two associated connecting links are disposed substantially in the central plane of said flap.

In accordance with an advantageous embodiment, the mobile control element corresponding to a flap is hooked into said kinematic chain at a point located on one of said two connecting links.

The present invention relates more particularly to the case where said first, second, third and fourth geometric axes relating to a controlled flap and to an intermediate lever adjacent same, are disposed in relation to one another in such a manner that the quadrilateral figure they define by their respective projections on to the central plane of said flap substantially takes the form of a parallelogram which deforms during the course of the variation in the nozzle section, said deformable parallelogram having a fixed side constituted by the straight line section linking together the projections, on said plane, of said first and second geometric axes, and a moving side which is substantially parallel to said fixed side and is constituted by the straight line section linking together the projections, on to said same plane, of said third and fourth geometric axes, said fixed side and said moving side being separated from one another by a variable interval constituting the height of the deformable parallelogram.

In accordance with a preferred embodiment applicable in this particular case, the point of hook-in of the mobile control element is disposed on one of said connecting links in a zone thereof which is located at any instant at a distance from the fixed side of the parallelogram, which is less than the height of the parallelogram. In this fashion, the efficiency of transmission of force between each control element and the corresponding controlled flap, is improved.

BRIEF DESCRIPTION OF THE DRAWINGS The invention will now be further described, by way of example, with reference to the accompanying drawings, in which:

FIG. 1 is a perspective view illustrating schematically the operation of a variable section nozzle equipped with a kinematic chain;

FIG. la is a diagram illustrating certain geometric features of said kinematic chain;

FIG. 2 is a longitudinal sectional view on a line IIIl of FIG. 3 of a variable section nozzle equipped with a kinematic chain in accordance with the present invention;

FIG. 2a is a view similar to that of FIG. 2, showing the nozzle in a different (open) configuration;

FIG. 3 is a plan view, partially cut away, of the nozzle shown in FIG. 2;

FIGS. 4, 5 and 6 are fragmentary transverse sectional DESCRIPTION OF PREFERRED EMBODIMENTS In FIG. 1, there has been schematically illustrated a portion of a variable section nozzle for a jet engine, equipped with a kinematic chain.

This nozzle comprises a fixed structure 1, which itself embodies a fixed nozzle casing (not shown), and a plurality of controlled flaps 2 distributed around and in extension of, the downstream portion of said fixed casing. Each flap 2 extends to either side of a central plane P containing the longitudinal axis of the nozzle and is articulated, about a first geometric axis A substantially tangential to the nozzle, to the fixed structure 1.

With each controlled flap 2 there corresponds a mobile control element 3 such as the rod of a jack 4, hooked into said flap and making it possible to pivot it about its pivot axis A in order to vary the transverse cross-sectional area of the nozzle.

A plurality of intermediate levers 5 (also known as synchronising levers) is arranged in alternation with the controlled flaps 2, each of them being articulated, about a second geometric axis B substantially tangential to the nozzle, to said same fixed structure I.

With each controlled flap 2 there are associated two connecting links 6 and 7 by means of which said flap is respectively connected to two successive intermediate levers surrounding it. Each link 6 or 7 is articulated, axis the one hand, about a third geometric axis C substantially tangential to the nozzle, to a controlled flap 2 and, on the other hand, about a fourth geometric axis D substantially tangential to the nozzle, to an intermediate lever 5 adjacent said flap.

As FIGS. 1 and 1a show, the four geometric axes A, B, C, D, associated with a controlled flap 2 and an intermediate lever 5 adjacent same, are disposed in relation to one another in such a fashion that the quadrilateral figure they define by their respective projections on to a plane containing the longitudinal axis of the nozzle (in the present instance the central plane P of the flap), is substantially a parallelogram ABCD which deforms during the course of the variations in the nozzle section.

This deformable parallelogram has a fixed side AB (see FIG. 1a) constituted by the straight line segment linking together the projections, on to the aforesaid plane, of the axes A and B; it also exhibits a moving side CD substantially equal and parallel to the side AB and constituted by the straight line segment which links together the projections, on to said same plane, of the axes C and D.

The assembly formed by the controlled flaps 2, the intermediate levers 5 and the connecting links 6 and 7, constitutes an indented kinematic chain, closed around the nozzle, which causes each of the controlled flaps 2 to take up a position common to the assembly of all the flaps. The nozzle thus, under all operating conditions and whatever the opening, retains a circular crosssection, concentric with itself, this even in the event of asymmetry in the operation of the mobile control elements 3 of said flaps.

The reference 311 designates the point of hookin to said kinematic chain, of the mobile control element 3 of a flap 2. As FIG. 1 shows, this point 3a is located in the central plane P of said flap.

Experience has shown that the arrangement which has just been described possesses a drawback which is due to the offset, in the peripheral direction, existing between on the one hand the point 3a at which the force is applied by the mobile control element 3, and, on the other hand, the connecting links 6 and 7 whose function is to distribute this force through the aforesaid kinematic chain. This offset is in effect a lever arm which results in the development of parasitic couples. synchronisation is still ensured but the component parts of the kinematic chain aforementioned, as well as the fixed structure of the nozzle 1, are subjected, as a consequence of the presence of these couples, to additional mechanical stresses. It is therefore necessary to reinforce these components and said structure, making them heavier, bulkier and more expensive.

There will now be described, in relation to FIGS. 2 to 7, a variable section nozzle equipped with a kinematic chain in accordance with the present invention, in which the drawback referred to is overcome or at any rate very substantially reduced.

This nozzle comprises a fixed structure 101 which itself embodies a nozzle casing 110 terminated at the rear by a reinforcing ring 1 l l and a plurality of longitudinal supporting beams 112 distributed in a regular manner around said casing, each of them taking the form of a yoke with a stem 1126 which splits into two arms 112a, 1 12b. Each of the supporting beams 112 is attached to the nozzle casing 110, on the one hand in the neighbourhood of its upstream end through the medium of a cross-member M attached to said casing by means which have not been shown, and, on the other hand, further downstream, through the medium of a pivot pin N passing through a lug 113 disposed at the periphery of the reinforcing ring 111.

The fixed nozzle casing is followed by a ring of pivotable flaps, comprising, on the one hand, controlled flaps 102 and, on the other, follower flaps 122. Each controlled flap 102 comprises a flap surface 102): fixed to a cranked lever 102y, the assembly constituted by said flap surface and said cranked lever having a symmetrical shape in relation to a central plane P passing through the longitudinal axis of the nozzle (see FIG. 3). Each cranked lever l02y is articulated, about a first geometric axis A substantially tangential in relation to the nozzle, to a yoke the two sides of which are formed by the arms 1 12a, 1 12b, ofa supporting beam 112. The follower flaps 112 are disposed respectively between the controlled flaps 102 and in operation they are applied against the intemal edges of their neighbours by the pressure of the gas stream flowing through the nozzle. An elastic annular apron (not shown) seals the joint between the fixed nozzle casing l 10 and the flaps With each controlled flap 102 there corresponds a mobile control element 103 constituted, for example, by the rod of a jack 104. The body of the jack, at its upstream end has two lugs 1040, 104b through the medium of which it is articulated about an axis R, to the two arms 112a, 1 12b of a supporting beam 112.

Intermediate or synchronising levers 105 (105 are articulated in each case about a second geometric axis B (B substantially tangential to the nozzle, to the stems 1126 of two peripherally successive supporting beams 112. It will be observed that the geometric axes B and B respectively, of two intermediate levers 105 105 which peripherally succeed one another, are offset in relation to one another in the longitudinal direction of the nozzle, in order that one of them (3,) is located upstream of the other (B The intermediate levers 105 and 105 are disposed in alternation with the controlled flaps 102 and each extend up to the neighbourhood of the respective central planes P of two successive controlled flaps. Two successive intermediate levers are disposed to either side of the central plane of each flap.

With each controlled flap 102 there are associated two connecting links 106, 107 by means of which said flap is respectively connected to two successive intermediate levers 105,, 105 Each link 106 (107) is articulated, on the one hand, about a third geometric axis C (C substantially tangential to the nozzle, to the lever l02y of a controlled flap 102, and, on the other hand, about a fourth geometric axis D (D substantially tangential to the nozzle, to an intermediate lever 105 (105 adjacent said flap. It will be observed that the two connecting links 106, 107 associated with one and the same controlled flap, are disposed substantially in the central plane P of said flap.

As FIGS. 2 and 2a show, the four geometric axes A, B (B C (C D (D associated with a controlled flap 102 and an intermediate lever 105, (105 adjacent the latter, are disposed in relation to one another in such a fashion that the quadrilateralfigure determined by their respective p'rojections on to the central plane P of said flap, substantially takes the forrh of a parallelogram AB,C D, (AB C D which deforms as the nozzle section varies. This parallelogram has a fixed side AB, (AB and a moving side C D '(C D substantially equal and parallel to said fixed side, .from which latter it is separated by a variable distance h constituting the height of the parallelogram. A

The assembly formed by the controlled flaps 102, the intermediate levers 105, and 105 and the connecting links 106 and 107, constitutes an indented kinematic chain, closed around the nozzle, which compels each of the controlled flaps 102 to adopt a mean position which is common to the assembly of all the flaps.

Each mobile control element 103 corresponding to a controlled flap, is hooked in at one end 103a, to the aforesaid kinematic chain at a point located in the central plane P of the flap. To this end, one of the two links 106, 107 associated with said flap, for example that 107, can be equipped with a lug 107a to which the end 103a of the control element 103 is hooked by means of a pivot pin F. It will be observed that in the example shown, the lug 107a of the connecting link 107, to which hooking in is effected, is located at any instant at a fixed distance 12' from the fixed side AB (AB of the parallelogram AB C D (AB C D which is less than the height h of the parallelogram.

FIG. 7 illustrates in a highly schematic fashion and in perspective, the kinematic chain fitted to the nozzle in accordance with the invention. To simplify illustration, only the levers 102 of the controlled flaps 102 (not the flap surfaces 102x of the flaps), have been shown, and it has been assumed furthermore that the axes C and C by means of which the levers l02y are respectively articulated to the connecting links 106 and 107, are coaxial.

By reason of the particular arrangement of connecting links 106 and 107 (which, for each controlled flap 102, are disposed, like the point of hook-in 1070 of the end 103a of the mobile control element 103, in the central plane P of said flap) the parasitic couples which develop in the known kinematic chain and to which reference has been made earlier, are eliminated at least to a very large extent.

In addition, because of the fact that in the kinematic chain in accordance with the invention the relationship h h (see FIG. 2) is always maintained, the links 107 act as force-transmitting elements. Thus, here the advantage is achieved that a substantial improvement in the efficiency of force transmission between each mobile control element 103 and the associated controlled flap 102 is obtained, this improvement being translated into terms either (for a given dimension of the jack 104) of an increase in the motive couple applied to the flap, or (for a given 44 motive couple) of a reduction in the dimensions (substantially the radial size) of said jack.

These combined advantages in turn lead to others,

crease the angle of deployment of the flaps (and there fore, for a given variation in noule section, to reduce the length of the flaps and especially the force applied to them), and an improvement in the conditions of flow of a secondary air flow between the jacks'. It should be noted, furthermore, that it is in" no way necessary for the various deformable parallelograrns such as AB C D and AB C D to have the same dimensions in moving from one flap to the next. In particular, it is possible to lengthen or shorten the intermediate levers and 105 the levers 102y of the controlled flaps 1'02 and the lever arm F C2, as required.

Thismeans that it'is possible, without altering the synchronising, to utilise jacks 104 and transmission and synchronising elements, whose size can vary from one location to another at the periphery of the nozzle. The result is that it is possible therefore to make the best possible" use of the space available around the nozzle.

The present invention is applicable equally well to simple" nozzles, comprising a single ring of controlled flaps (as was the case in the nozzle just described), and to composite flame tube systems comprising two rings of controlled flaps associated respectively with a primary nozzle and a secondary nozzle.

It goes without saying that the embodiment described is purely an example and is open to modification, in particular by the substitution of equivalent techniques without in so doing departing from the scope of the invention as defined in the claims.

What is claimed is:

1. In a variable-section nozzle of the type comprising a fixed structure embodying a fixed nozzle casing; a plurality of controlled flaps distributed around and in extension of the downstream portion of said fixed nozzle casing, each of which flaps extends to either side of a central plane containing the longitudinal axis of the nozzle, and is articulated about a first geometric axis disposed substantially tangential in relation to the nozzle, to said fixed structure; a plurality of intermediate levers disposed in alternation with said controlled flaps, each articulated, about a second geometric axis substantially tangential in relation to the nozzle, to said fixed structure; a plurality of connecting links each of which is articulated on the one hand about a third geometric axis substantially tangential in relation to the nozzle, to a controlled flap, and, on the other hand, about a fourth geometric axis substantially tangential in relation to the nozzle, to an intermediate lever adjacent said flap in order that each control flap is respectively attached to two successive intermediate levers, the assembly formed by said controlled flaps, said intermediate levers and said connecting links, constituting a kinematic chain which is closed around the nozzle; and a plurality of mobile control elements each of which corresponds with a controlled flap and makes it possible to pivot said flap about said first geometric axis in order to vary the transverse cross-section of the nozzle, the improvement wherein each intermediate lever extends up to the neighbourhood of the respective central planes of two successive controlled flaps; and wherein for each controlled flap, the two associated connecting links are disposed substantially in the central plane of said flap.

2. A nozzle as claimed in claim 1, in which said mobile control element corresponding to a flap is hooked into said kinematic chain at a point located on one of said two connecting links.

3. A nozzle as claimed in claim 2, in which said first, second, third, and fourth geometric axes relating to a controlled flap and an adjacent intermediate lever, are disposed in relation to one another such that the quadrilateral figure defined by their respective projections on to the central plane of said flap, is substantially a parallelogram which deforms as the nozzle section varies, said deformable parallelogram having a fixed side constituted by the straight line segment linking together the projections, on to said plane, of said first and second geometric axes, and a moving side substantially parallel to said fixed side and constituted by the straight line segment linking together the projections on said same plane, of said third and fourth geometric axes, said fixed side and said moving side being separated from one another by a variable interval which constitutes the height of the deformable parallilogram, wherein said point of hookin of the mobile control element is located in a zone of said connecting link which is disposed at any instant at an interval from the fixed side of the parallelogram, which is less than the height of said parallelogram.

4. A nozzle as claimed in claim 3, in which the respective geometric axes of two successive intermediate levers are otTset in relation to one another in the longitudinal direction of the nozzle so that one is disposed upstream of the other.

5. A nozzle as claimed in claim 4, in which two successive intermediate levers are disposed on either side of the central plane of each flap. 

1. In a variable-section nozzle of the type comprising a fixed structure embodying a fixed nozzle casing; a plurality of controlled flaps distributed around and in extension of the downstream portion of said fixed nozzle casing, each of which flaps extends to either side of a central plane containing the longitudinal axis of the nozzle, and is articulated about a first geometric axis disposed substantially tangential in relation to the nozzle, to said fixed structure; a plurality of intermediate levers disposed in alternation with said controlled flaps, each articulated, about a second geometric axis substantially tangential in relation to the nozzle, to said fixed structure; a plurality of connecting links each of which is articulated on the one hand about a third geometric axis substantially tangential in relation to the nozzle, to a controlled flap, and, on the other hand, about a fourth geometric axis substantially tangential in relation to the nozzle, to an intermediate lever adjacent said flap in order that each control flap is respectively attached to two successive intermediate levers, the assembly formed by said controlled flaps, said intermediate levers and said connecting links, constituting a kinematic chain which is closed around the nozzle; and a plurality of mobile control elements each of which corresponds with a controlled flap and makes it possible to pivot said flap about said first geometric axis in order to vary the transverse cross-section of the nozzle, the improvement wherein each intermediate lever extends up to the neighbourhood of the respective central planes of two successive controlled flaps; and wherein for each controlled flap, the two associated connecting links are disposed substantially in the central plane of said flap.
 2. A nozzle as claimed in claim 1, in which said mobile control element corresponding to a flap is hooked into said kinematic chain at a point located on one of said two connecting links.
 3. A nozzle as claimed in claim 2, in which said first, second, third, and fourth geometric axes relating to a controlled flap and an adjacent intermediate lever, are disposed in relation to one another such that the quadrilateral figure defined by their respective projections on to the central plane of said flap, is substantially a parallelogram which deforms as the nozzle section varies, said deformable parallelogram having a fixed side constituted by the straight line segment linking together the projections, on to said plane, of said first and second geometric axes, and a moving side substantially parallel to said fixed side and constituted by the straight line segment linking together the projections on said same plane, of said third and fourth geometric axes, said fixed side and said moving side being separated from one another by a variable interval which constitutes the height of the deformable parallilogram, wherein said point of hookin of the mobile control element is located in a zone of said connecting link which is disposed at any instant at an interval from the fixed side of the parallelogram, which is less than the height of said parallelogram.
 4. A nozzle as claimed in claim 3, in which the respective geometric axes of two successive intermediate levers are offset in relation to one another in the longitudinal direction of the nozzle so that one is disposed upstream of the other.
 5. A nozzle as claimed in claim 4, in which two successive intermediate levers are disposed on either side of the central plane of each flap. 